Toyota Yaris Mk2 2006 passenger door wont lock sometimes with key fob

[avensisd4d786]

sometimes it will lock sometimes it wont with key fob and key in drivers door

any suggestions 

[flash22]

A bad door lock mech/solenoid ? re-lube the lock with gt-85 or ptfe (not wd40)

Electrical, a corroded connector, A wire starting to break in the rubber bellows or a poor ground

[stantheman1]

Excellent advice above.

[Cyclopse11]

I did one of these on my driver door recently. Quite straight forward and good guidance onYouTube. Please note you can remove the internal handle once the door panel is removed which makes it easier because there is more space. Unfortunately the electrical motors go bad over time and the electrical operation is then affected.